Ethylene polymers such as high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and ultrahigh molecular weight polyethylene (UHMWPE) can be obtained by polymerizing ethylene, optionally in mixture with higher alpha olefins, in the presence of a coordination catalyst. One type of coordination catalyst is constituted by the Ziegler-Natta (ZN) catalyst. The polymerization processes can involve the use of a solid catalyst component made from or containing magnesium chloride based supports on which an active metal (such as titanium chloride) is fixed. In some instances, the resulting procatalyst is activated for polymerization by reacting the procatalyst with an organoaluminum compound.
In some instances, the procatalyst is produced according to different preparation routes, which impart specific characteristics to the procatalyst. In the ethylene polymerization field, a catalyst feature is polymerization activity. Additional catalyst features are the capability of the catalyst to produce ethylene polymers with high intrinsic viscosity (UHMWPE) and the capability of the catalyst to distribute the comonomer (higher alpha olefin) into the polyethylene chain for producing LLDPE.